package com.wongoing.util.safe.aes;

import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;

import org.apache.commons.codec.binary.Base64;

import com.wongoing.util.ImageUtil;
import com.wongoing.util.LogService;

public class AESHelper {
	
	 private static final String KEY_ALGORITHM = "AES";
	 private static final String DEFAULT_CIPHER_ALGORITHM = "AES/ECB/PKCS5Padding";//默认的加密算法
	 
	 private static AESHelper instance;
		
		/**
		 * 定义私有构造方法实现单例
		 */
		public AESHelper() {
			super();
		}

		public synchronized static AESHelper getInstance() {
			if(instance == null) {
				instance = new AESHelper();
			}
			return instance;
		}
	 /**
     * AES 加密操作
     *
     * @param content 待加密内容
     * @param password 加密密码
     * @return 返回Base64转码后的加密数据
     */
    public String encrypt(String content, String password) {
        try {
            Cipher cipher = Cipher.getInstance(DEFAULT_CIPHER_ALGORITHM);// 创建密码器
            byte[] byteContent = content.getBytes("utf-8");
            cipher.init(Cipher.ENCRYPT_MODE, getSecretKey(password));// 初始化为加密模式的密码器
            byte[] result = cipher.doFinal(byteContent);// 加密
            return Base64.encodeBase64String(result);//通过Base64转码返回
        } catch (Exception ex) {
          LogService.getInstance(this).info("aes加密错误：", ex);
        }
        return null;
    }

    /**
     * AES 解密操作
     *
     * @param content
     * @param password
     * @return
     */
    public String decrypt(String content, String password) {
        try {
            //实例化
            Cipher cipher = Cipher.getInstance(DEFAULT_CIPHER_ALGORITHM);
            //使用密钥初始化，设置为解密模式
            cipher.init(Cipher.DECRYPT_MODE, getSecretKey(password));
            //执行操作
            byte[] result = cipher.doFinal(Base64.decodeBase64(content));
            return new String(result, "utf-8");
        } catch (Exception ex) {
        	 LogService.getInstance(this).info("aes解密错误：", ex);
        }
        return null;
    }

    /**
     * 生成加密秘钥
     *
     * @return
     */
    private SecretKeySpec getSecretKey(final String password) {
        //返回生成指定算法密钥生成器的 KeyGenerator 对象
        KeyGenerator kg = null;
        try {
            kg = KeyGenerator.getInstance(KEY_ALGORITHM);
            //AES 要求密钥长度为 128
            kg.init(128, new SecureRandom(password.getBytes()));
            //生成一个密钥
            SecretKey secretKey = kg.generateKey();
            return new SecretKeySpec(secretKey.getEncoded(), KEY_ALGORITHM);// 转换为AES专用密钥
        } catch (NoSuchAlgorithmException ex) {
            
        }
        return null;
    }
    
}
